Title

Authors

Date of Completion

January 2006

Keywords

Psychology, Developmental

Degree

Ph.D.

Abstract

The current study examined social behavior in the first year of life, focusing on developmental changes in infants' coordinated expressive behaviors during face-to-face interaction. We extended the age range of previous research, which has focused primarily on the first 6 months, and examined infants' communicative behaviors at 4, 7, and 10 months of age. In contrast to prior work, which has examined coordinated behaviors mainly across two modalities, we simultaneously investigated co-occurring relations between infant looking, facial expressions, and vocalizations. Also, we investigated the unique stimulus values of maternal vocal activity by observing differential variations in infants' coordinated behaviors to the cessation of maternal vocalizations. Lastly, we examined the influence of a novel social partner on infants' cross-modal organizations. Besides microlevel analyses, we conducted standard correlations between behaviors as we'll as global ratings of infants' and mothers' interactive behaviors. ^ Infant looking, facial expressions, and vocalizations coalesced systematically in relation to age and interactional context. There was developmental progress towards greater complexity in the organizations of infants' expressive behaviors, particularly in the second half-year of life. At 10 months of age, infants showed a greater proficiency in combining facial and vocal displays of positive affect to communicate their social interest in people as well as objects. Infants of all ages responded to the cessation of maternal vocalization with decreased smiling. However, 10-month-olds also responded with an increase in their non-distress vocalizations, and were given high sociability ratings in this condition. For 4- and 7-month-olds, novel partners seemed to elicit more social and more positive behavioral displays compared to infants' mothers. These findings contribute to a clearer picture of the development of infants' expressive behaviors across the first year of life.^